一种在测量人工耳蜗使用者的调幅检测时动态控制不必要响度线索的方法。
A method to dynamically control unwanted loudness cues when measuring amplitude modulation detection in cochlear implant users.
作者信息
Galvin John J, Fu Qian-Jie, Oba Sandy, Başkent Deniz
机构信息
Division of Communication and Auditory Neuroscience, House Research Institute, Los Angeles, CA, USA; University of California Los Angeles, David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, USA; Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Research School of Behavioral and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands.
Division of Communication and Auditory Neuroscience, House Research Institute, Los Angeles, CA, USA; University of California Los Angeles, David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, USA.
出版信息
J Neurosci Methods. 2014 Jan 30;222:207-12. doi: 10.1016/j.jneumeth.2013.10.016. Epub 2013 Nov 20.
BACKGROUND
Amplitude modulation (AM) detection is a measure of temporal processing that has been correlated with cochlear implant (CI) users' speech understanding. For CI users, AM stimuli have been shown to be louder than steady-state (non-AM) stimuli presented at the same reference current level, suggesting that unwanted loudness cues might contribute to CI users' AM sensitivity as measured in a modulation detection task. In this paper, a new method is introduced to dynamically control unwanted AM loudness cues when adaptively measuring modulation detection thresholds (MDTs) in CI users.
METHODS
MDTs were adaptively measured in 9 CI subjects using a three-alternative, forced-choice procedure, with and without dynamic control of unwanted AM loudness cues. To control for AM loudness cues during the MDT task, the level of the steady-state (non-AM) stimuli was increased to match the loudness of the AM stimulus using a non-linear amplitude scaling function, which was obtained by first loudness-balancing non-AM stimuli to AM stimuli at various modulation depths. To further protect against unwanted loudness cues, ±0.75dB of level roving was also applied to all stimuli during the MDT task.
RESULTS
Absolute MDTs were generally poorer when unwanted AM loudness cues were controlled. However, the effects of modulation frequency and presentation level on modulation sensitivity were fundamentally unchanged by the availability of AM loudness cues.
CONCLUSIONS
The data suggest that the present method controlling for unwanted AM loudness cues might better represent CI users' MDTs, without changing fundamental effects of modulation frequency and presentation level on CI users' modulation sensitivity.
背景
调幅（AM）检测是一种时间处理测量方法，已被证明与人工耳蜗（CI）使用者的言语理解相关。对于CI使用者，已表明在相同参考电流水平下呈现的AM刺激比稳态（非AM）刺激更响亮，这表明在调制检测任务中测量的CI使用者的AM敏感性可能受到不必要的响度线索的影响。本文介绍了一种新方法，用于在自适应测量CI使用者的调制检测阈值（MDT）时动态控制不必要的AM响度线索。
方法
使用三选一强制选择程序，对9名CI受试者进行自适应MDT测量，测量时有无对不必要的AM响度线索进行动态控制。为了在MDT任务中控制AM响度线索，使用非线性幅度缩放函数将稳态（非AM）刺激的水平提高，以匹配AM刺激的响度，该函数是通过首先在各种调制深度将非AM刺激与AM刺激进行响度平衡而获得的。为了进一步防止不必要的响度线索，在MDT任务期间，还对所有刺激应用了±0.75dB的电平游动。
结果
当控制不必要的AM响度线索时，绝对MDT通常更差。然而，AM响度线索的存在并未从根本上改变调制频率和呈现水平对调制敏感性的影响。
结论
数据表明，目前控制不必要的AM响度线索的方法可能能更好地反映CI使用者的MDT，而不会改变调制频率和呈现水平对CI使用者调制敏感性的基本影响。
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